Digital printing, though still an expensive method of printing, is now becoming more popular with a number of quality brands for its capability to print designs not possible in rotary printing and in a choice of colours and intricacy of patterns not achievable otherwise, thereby helping them in their fight against counterfeiting: The brands employ designs which can only be achieved by using this technology and cannot be copied by any other method. Leading the way is Digital Print Asia, originally started as a joint venture between the Yeh Group and Stork Prints of Netherlands and today a company wholly owned by the Yeh Group. Catering to the needs of buyers such as adidas, DPA offers a capacity of 700,000 linear metres per annum and is known in the industry for digital printing directly onto the fabric.
Starting in 2002 with only three printers, DPA today has twenty digital printing machines making it one of the three largest digital direct to fabric printers in the world and the largest to specialise in swimwear, sportswear and intimate wear. Pigment, disperse, reactive and acid dyes are all used depending on the base fabric, and all but the disperse dyes have to be subsequently steamed and finished.
Of the printing units available in Digital Print Asia, most are of the Mimaki TX2. Each machine can run all ink types, whether reactive, acid, disperse or pigment, and all type of fabrics can be printed, from rigid wovens to elastic knits with or without elastomers. To help with the elastomers, some of the printers have an additional printing belt installed to help ensure the fabric is printed in its relaxed state.
The plant’s total capacity averages 700,000 meters per annum with the machines operating twenty hours per day, each printing an average of ten metres per hour. If one machine goes out of commission, there is still plenty of capacity on the other working machines. Currently 10-15% of the fabric printed is converted into garments locally. Although DPA does not have an inhouse garmenting facility, the stitching is done at YehPattana-Tayeh or YehParfun, both part of the Yeh Group of companies, just like DPA.
Depending on the orders and delivery dates, twenty different designs can be printed simultaneously or several machines can be set up to print the same design at the same time, enabling maximum flexibility. The machines utilise the well-known Epson type print heads, commonly used throughout the market. Printing is very often carried out at resolutions of 360×540 or 720×720 dots per inch(dpi) with variable drop quantities for optimum quality. The average digital print run at DPA is 1000-2000 linear metres, but it actually ranges from one metre to 27,000 metres, and the maximum fabric width that can be printed is 160 centimetres.
The process of digital printing has many financial, design and quality implications, thereby resulting in barely 2% of the world’s fabric being printed using this method. In terms of cost, digital printing is normally compared to rotary screen-printing. With digital printing, there are no setting up costs and no screens to develop. In addition, an image can be printed directly from the computer file onto the fabric and so can be produced immediately on demand. Digital printing neither offers a minimum length nor a repeat length and can do an unlimited number of colours per design. Also, designs can be corrected on the fly at no additional cost.
However, in rotary printing, the pattern is produced by overlaying a limited number of screens, normally between eight and twelve using pre-mixed inks based on carefully monitored dye recipes. Thus, before any printing can be carried out, processes such as colour separation and preparation, repeat management and screen engraving have to be done. Any change in design necessitates changes in screens and therefore, increased cost.
Even though digital printing inks reduce the original cost to one/tenth, they are still very expensive compared to rotary print dyes, averaging around €10 per square metre. Thus, as the cost of the screens has to be amortized over the print run, the longer the print run, the cheaper the rotary printing per metre becomes, compared to digital printing, where the price per metre remains the same whether fifty or five hundred metres are required.
In addition, twelve rotary screens may cost up to US$500 each, i.e. $6,000 per design, which has to be paid for before the cost of the design can be said ‘to break even’. The cost comparison for each design has to be individually calculated, but basically, the printing of short runs is cheaper using digital printing and long runs are cheaper when rotary printed. The subsequent processes such as steaming and finishing remain the same, whether digital or rotary printed. Digitally printed fabrics however need to be pretreated with a mixture of sodium bicarbonate, urea, thickener and water, which is actually comparable to the printing paste used in rotary printing.
[bleft]The average digital print run at DPA actually ranges from one metre to 27,000 metres with a maximum fabric width of 160 centimetres an image can be printed directly from the computer file onto the fabric[/bleft]
Other considerations that come into play are quality and design issues. With rotary, the number of colours within a design is limited to the number of screens being used, plus the base colour of the fabric. Digital provides for sixteen million colours and needs no separations. For the 2006 Torino Olympic Games, for example, Adidas commissioned DPA to produce 25,000 metres of digitally printed fabric for their sportswear. The reason they wanted digitally printed fabric rather than a rotary print was partially due to the fine colour gradation that digital can produce but rotary cannot, the sharpness which can be achieved, and the ready ability to grade the size of design so that the end product looks the same on a small person and on an extra large person.
There are many designs that can be digitally printed which just cannot be achieved using rotary printing. Also, designs can be engineered to achieve different effects to save printing ink; only the part of the fabric going into the garment can be printed, thus saving expensive ink.
Digital printing requires much know how. The resolution used, the amount of ink, the temperature and humidity of the print room, even the distance of the ink jet nozzles from the fabric, all have an effect on quality. Sometimes a lower print resolution can produce a nicer and crisper looking print than a very high resolution. Pre and post treatments react in different ways with the ink dyes and the end use of the garment has to be taken into consideration. With sportswear, for example, the dyes must not change colour with perspiration and washing, whereas swimwear needs to be seawater and chlorine resistant. Another factor that needs to be kept in mind is the print quality requirement of the buyer. For example, if someone needs a print with a high light fastness on polyester, then, inks specifically designed for the purpose are used. DPA procures ink from multiple suppliers such as Stork, Huntsmann and Dystar.
The most recent customers of digital print are adidas, Speedo, Nike and Puma for their sport and swimwear lines, as well as more fashion-oriented brands including Custo, Coach, Paul Smith and Ralph Lauren.
Sublimation Print Asia, also part of the YEH Group, produces sublimation papers that are used to print polyester sportswear material and has a capacity of about 200.000 linear metres per month. Sublistatic printing done by the company is only suitable for polyester garments. Again screens are required for the printing of the paper and thus the designs are again limited in their gradation and colour range. But then, no post treatment is required and thus become cheaper than traditional rotary printing.
In terms of future development Yeh is looking into several areas. With the ongoing reduction in the cost of digital print inks, the cost of printing is expected to reduce and thus expansion of DPA will be inevitable. The Group is also experimenting with waterless dyes based on liquid CO2, which are very environment friendly. The new laminating business of the group has opened up many new potential ‘special fabrics’.
Technical textiles, especially digitally printed car interior fabrics, are a potential area for development, especially for the European market and with the newly acquired FTA with Japan, the Japanese market. However, Thailand is a member of ASEAN, one of the fastest growing areas in the world, with a population of over 500 million, greater than the EU, with a growing wealth and an internal Free Trade Agreement. This provides much scope for new Thai brands. The member countries of ASEAN, though, still appear to prefer well-established Western brands to local ones. In this environment, Yeh is developing its own brand name within the West, which, once established, will be marketed throughout the ASEAN countries, with the new brand not appearing necessarily as a Thai brand. The ASEAN free trade agreements also provide much scope for export of fabrics within ASEAN. Most of the ASEAN countries are clothing producers, but only Thailand and Indonesia are fabric producers. Where FTA rules of origin provide for fabric to be made in ASEAN. This is a severe limitation on other ASEAN countries as the rule only gives a choice of two countries.